The present invention relates to a drawer sliding device. More particularly, the invention relates to a drawer sliding device for selectively manually sliding a drawer into and out of a frame. The device of the invention relates to drawers, trays, gates, and any other extension bar supported devices.
As is well known, drawers of filing cabinets, kitchen cabinets and other furniture or related mechanical devices, destined to carry loads or articles relatively heavy, produce, when filled, a certain amount of friction against sliding open, which hampers their use. For this reason, they generally make use of guides and slides of various kinds, bearings, weight balances, and other devices. For the sake of simplicity, all these devices are hereinafter referred to as just "drawers".
Of the various kinds of known drawer slides, a common one is the slide extension which slides out half way for any distance that the drawer itself is pulled out to. This is, in general, accomplished in the following manner. The slide extension has rollers positioned at its center. The rollers contact with the drawer on one side and the cabinet frame on the other, in such a way that when the drawer is pulled out or pushed in, the rollers, and consequently the slide extension bar, moves just half the distance travelled by the drawer. Another condition that must be observed is that resistance to slippage must always be greater between the points of contact of the roller with the drawer and frame, rather than between the extension slide bar and the aforementioned drawer and cabinet parts, so that the roller cannot slip with respect to either one of them. In common designs, this feature is obtained by loading of the rollers. In a filing cabinet, for example, the whole weight of the drawer is supported by these rollers. However, as the drawer is moved, the weight center moves also, falling away from the position of the central rollers. In a common way, this difficulty is overcome by installing more than one set of rollers, so that at any position, at least one of them fulfills the above stipulated requirement.
Devices of the aforedescribed type, however, aside from increasing cost, are satisfactory primarily for steel drawer devices. Their application to, for example, common, wooden furniture is inconvenient from the standpoint of slide attachment precision requirements and the availability of limited choices of lengths of slides. The drawer sliding device of the invention may be applied as a separate added device to metal furniture, wood furniture, or plastic, equally well, or by incorporating the design directly into the fabricated shapes of the foregoing, since the concept is simple, adding little cost to the drawer devices.
The drawer sliding device of the invention, similarly to conventional devices, also travels half the distance travelled by the drawer of the device with respect to the cabinet frame. This is accomplished by a roller in contact with the fixed frame and the moving drawer part. The roller is supported by the slide extension bar. The contact between the roller and the other parts of drawer and cabinet are not, however, only due to planar loading, but are also as a consequence of torque along the slide extension bar, which guarantees the application of necessary contact.
Generally, the drawer sliding device of the invention comprises longitudinal bars or slide extensions that rest in grooves placed for the support of the drawer in the frame and, likewise, along the drawer. The shapes of the grooves are such as to permit a limited amount of torsion of the slide extension bar along them. At the center of the bars are located rollers that roll against the drawer at one point and the support frame for the drawer at an opposite point, and they rotate during the sliding of the drawer. The bars of each drawer may be singular for each drawer device or, more commonly, may be in pairs, as hereinafter described. The bars are restrained to alignment by specific guide features between such bars and corresponding positions along the channels. The bars of each drawer may eventually be connected between each other by linkages for better alignment, durability, performance and support.
The aforedescribed device in a general way offers a series of advantages, once the conditions that ensue from the fundamental principle of the invention are carried out.
The rollers are positioned in such a manner that during the entire projected traversal, during the entire relative motion between the different components of the drawer, the prescribed roller contact is always maintained, and applied loads will always produce the torsion of the extension bars of the slide applying tightness against the rollers. If, under certain conditions, this tightness is not always attainable, the rollers' own weight or certain spring-loading or similar mechanical means could also be used to supplement it.
At least one generally centrally located roller is mounted in each extension bar. Whenever the net force of the drawer loading is applied to the extension bar, the resulting torsion in said bar is always carried through to the rollers. Similarly, the change of position of the drawer causes no adverse effect. A greater number of rollers or bearing balls, or the like, may be used per slide, for greater versatility of the device. With this end in mind, it is also possible to have a larger number of pairs of contact points between rollers and both halves of a drawer assembly.
The friction between any portion of the two parts of the drawer assembly flange and frame and the slide or extension bar could also be eliminated or reduced by other friction reducing devices placed anywhere and in any position, similar to some other commonly known arrangements for slides, and so on. It is also possible to use to this end proper friction reducing devices or rollers for other typical functions of the device as well as other guides or other devices destined to augment proper functioning of the slides.
The practical design for the contact points between a central roller and the other parts of the drawer assembly must exhibit enough friction drag superior at least to any other drag that might exist elsewhere between the slide extension and parts in relative motion to it.
As hereinbefore mentioned, a drawer may be made with more than one slide assembly. Other types of guide methods may be applied together with the slides at hand. The forms of such additional guides and slides must be such as never to obstruct the necessary freedom for torsion of the bars at hand. The direction of the required torsion axis in a bar can also be so chosen as to control the amount of clearance among the components of the slide assembly, in general, or for a particular slide position.
It is further possible to apply to the invention a multiplicity form, by making simultaneous use of several of the described extension bars or slides, one operating inside the other, in order to obtain greater extension between the support components of the drawer.
Another feature of the invention is that it can have front to back symmetry and thus operate equally forward as to the rear. This capability can be utilized so that a given length slide, installed near the forward end of a drawer can service a drawer twice its nominal length, by extending inward when the drawer is closed.
The rollers may also not be required to support the entire loading applied between the support components of the drawer, so that the torsion applied need not apply excessive strain to the axles of the rollers, especially if the extension bars are made of fibrous or plastic materials.
Objects of the invention are to provide a drawer sliding device of simple structure, which is inexpensive in manufacture, parts of which are readily fabricated as integral features of the drawer or frame, or which can incorporate assembly aids to improve and accelerate that process, and functions efficiently, effectively and reliably to provide good, low friction, sliding support for a drawer. The drawer sliding device of the invention has the advantages of low demand on tight tolerances for assembly and operation, severability to a desired length with a hacksaw, or similar tool, for do-it-yourself, versatility and handyman applications, extendability in either of two opposite end directions, removability of the drawer with or without releases, adaptability of adjustable or fixed drawer stops, and applicability to a multitude of different applications.